Apparatus that operates with compressed air and is adjustable to either blow air or create a vacuum for cleaning machinery is known in the prior art. See, for example, U.S. Pat. No. 1,078,512 to Mills, U.S. Pat. No. 3,525,118 to Viollet, U.S. Pat. No. 3,683,446 to Tell and British Patent No. 1,211,930 to Herre.
The Herre patent is the closest known prior art to applicants' invention. Herre employs an air gun with an "ejector" or venturi tube to create a suction with compressed air. The suction currents empty through a flexible tube into a fabric container. The compressed air is redirected to blow from Herre's air gun when the flexible tube is closed by manually pinching it together, and thereby redirecting the compressed air to blow outwardly from the air gun.
In the Herre apparatus, the suction currents are directed out the back of the gun, toward the operator using the device, possibly projecting debris against the operator and causing serious injury. Herre's flexible pinch tube could be in advertently bent to accidentally close the tube during a vacuum function, causing the air and debris collected during the suction function to change direction and be blown out the nozzle with possible damage.
Compressed air is conventionally delivered at a pressure of 80 pounds per square inch (80 psi) to pneumatic equipment in factories, but the Occupational Safety Hazards Act (OSHA) limits the air pressure to 30 psi when compressed air is blown into the ambient air of a factory. The apparatus disclosed in the British patent to Herre will not meet OSHA's 30 psi regulation.
These safety hazards, and others, are overcome by the present invention.